This article explains how static/access-internal routes are applied with the LTE module.

The following scenarios apply for access-internal and static routes:

1. Adding ISP IP address as next-hop

set routing-options static route 8.8.8.8/32 next-hop x.x.x.x; <-- This is the ISP IP address ​

2. Adding dl0.0 as next-hop for the LTE always-on option ​

As per the technical documentation on Configuring LTE Interfaces , to activate the dial-on-demand feature, you need to set 'dl0.0' as the next-hop of a route to trigger dial out. 

set routing-options static route <route> next-hop dl0.0

However, when using the always-on option:

set interfaces dl0 unit 0 dialer-options always-on

it is not possible to add a route and set 'dl0.0' as the next-hop.

RPD does not support adding the LTE ISP IP address (x.x.x.x) and the dialer interface (dl0.0) being used as the next-hop and routes will not be installed on the forwarding table. 

1. Adding an ISP IP address as the next-hop

Starting with Junos OS release 15.1X49-D200, 15.1X49-D210, 18.2R3-S3, 18.3R3-S1, 18.4R3, 19.1R3, 19.2R2, 19.3R3, 19.4R2, and 20.1R1, the following is correctly applied:

set routing-options static route 8.8.8.8/32 next-hop x.x.x.x;  <-- This is the ISP IP address ​

2. Adding dl0.0 as the next-hop for the LTE always-on option

Route configuration such as 'set routing-options static route 8.8.8.8/32 next-hop dl0.0' does not work.

The following configuration knob was introduced starting with Junos OS release 15.1X49-D170, 15.1X49-D180, 18.2R2, 18.2X85-D10, 18.3R2, 18.4R1, and 19.1R1​:

set interfaces dl0 unit 0 dialer-options route 8.8.8.8/32

The 'dialer-options route' configuration in the LTE interface does not work in the user-defined routing instance. It works only in the root routing instance.

2020-09-29: Adding NFX150, since this also supports LTE module